OBJECTIVES: Unplanned cardiac reinterventions (UCR) after congenital cardiac surgery may complicate the post-operative course. We sought to identify incidence rates and risk factors for UCRs and associations between UCRs and hospital mortality. METHODS: Patients in the Pediatric Cardiac Critical Care Consortium (PC RESULTS: Included were 34,495 patients from 62 centers. UCRs occurred in 2,635 (7.6%) patients with wide center variation. Risk factors for UCR included Black race, extracardiac and chromosomal anomalies, younger age, lower weight for age, prior cardiac surgeries, and higher surgical complexity category. The performance of an UCR was associated with higher hospital mortality (16.1%) compared to those who did not undergo reintervention (1.3%) (aOR, 6.45
95% CI, 5.51-7.56, P<
0.001). The odds of mortality after UCR increased with higher STAT-EACTS category. Mortality was highest in patients who underwent both reoperation and interventional catheterization (31.9%) compared to those who only underwent reoperation (16.3%) or catheterization (9.8%). CONCLUSIONS: UCRs occur in approximately one in 13 patients after congenital cardiac surgery, and approximately one in six patients with an UCR will die. Patients at greatest risk for UCR may share patient and disease-specific risk factors. Further investigation is needed to minimize the incidence of residual lesions, understand why Black children have more UCRs, and explore modifiable risk factors for and optimal timing of UCRs.